﻿using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;

namespace Marmat.Data
{

    /// <summary>
    /// 对称加密算法类
    /// </summary>
    public class SymmetricMethod
    {
        private SymmetricAlgorithm mobjCryptoService;
        private string Key;
        /// <summary>
        /// 对称加密类的构造函数
        /// </summary>
        public SymmetricMethod(string Key)
        {
            if (string.IsNullOrEmpty(Key) || Key is null)
            {
                this.Key = "Guz(%&hj7x89H$yuBI0456FtmaT5&fvHUFCy76*h%(HilJ$lhj!y6&(*jkP87jH7";
            }
            else
            {
                this.Key = Key;
            }

            this.mobjCryptoService = new RijndaelManaged();
        }

        /// <summary>
        /// 对称加密类的构造函数
        /// </summary>
        public SymmetricMethod()
        {
            this.mobjCryptoService = new RijndaelManaged();
            this.Key = "Guz(%&hj7x89H$yuBI0456FtmaT5&fvHUFCy76*h%(HilJ$lhj!y6&(*jkP87jH7";
        }
        /// <summary>
        /// 获得密钥
        /// </summary>
        /// <returns>密钥</returns>
        private byte[] GetLegalKey()
        {
            string sTemp = this.Key;
            this.mobjCryptoService.GenerateKey();
            var bytTemp = this.mobjCryptoService.Key;
            int KeyLength = bytTemp.Length;
            if (sTemp.Length > KeyLength)
            {
                sTemp = sTemp.Substring(0, KeyLength);
            }
            else if (sTemp.Length < KeyLength)
            {
                sTemp = sTemp.PadRight(KeyLength, ' ');
            }

            return Encoding.ASCII.GetBytes(sTemp);
        }
        /// <summary>
        /// 获得初始向量IV
        /// </summary>
        /// <returns>初试向量IV</returns>
        private byte[] GetLegalIV()
        {
            string sTemp = "E4ghj*Ghg7!rNIfb&95GUY86GfghUb#er57HBh(u%g6HJ($jhWk7&!hg4ui%$hjk";
            this.mobjCryptoService.GenerateIV();
            var bytTemp = this.mobjCryptoService.IV;
            int IVLength = bytTemp.Length;
            if (sTemp.Length > IVLength)
            {
                sTemp = sTemp.Substring(0, IVLength);
            }
            else if (sTemp.Length < IVLength)
            {
                sTemp = sTemp.PadRight(IVLength, ' ');
            }

            return Encoding.ASCII.GetBytes(sTemp);
        }
        /// <summary>
        /// 加密方法
        /// </summary>
        /// <param name="Source">待加密的串</param>
        /// <returns>经过加密的串</returns>
        public string Encrypto(string Source)
        {
            var bytIn = Encoding.UTF8.GetBytes(Source);
            var ms = new MemoryStream();
            this.mobjCryptoService.Key = this.GetLegalKey();
            this.mobjCryptoService.IV = this.GetLegalIV();
            var encrypto__1 = this.mobjCryptoService.CreateEncryptor();
            var cs = new CryptoStream(ms, encrypto__1, CryptoStreamMode.Write);
            cs.Write(bytIn, 0, bytIn.Length);
            cs.FlushFinalBlock();
            ms.Close();
            var bytOut = ms.ToArray();
            return Convert.ToBase64String(bytOut);
        }
        /// <summary>
        /// 解密方法
        /// </summary>
        /// <param name="Source">待解密的串</param>
        /// <returns>经过解密的串</returns>
        public string Decrypto(string Source)
        {
            var bytIn = Convert.FromBase64String(Source);
            var ms = new MemoryStream(bytIn, 0, bytIn.Length);
            this.mobjCryptoService.Key = this.GetLegalKey();
            this.mobjCryptoService.IV = this.GetLegalIV();
            var encrypto = this.mobjCryptoService.CreateDecryptor();
            var cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Read);
            var sr = new StreamReader(cs);
            return sr.ReadToEnd();
        }
    }
}